EP2206819B1 - Thread cutting device for a sewing machine - Google Patents

Abstract

The device has a counter blade (115) fixed to a base plate. A cutting edge (116) of a movable thread cutting blade is limited by a cutting-wall section (119) of an upper thread drawing blade wall (119a) of the cutting blade. The wall passes into a distance-wall section (121) beyond the cutting edge, so that the cutting blade adjacent to the cutting edge comes in contact with the counter blade during thread cutting. The distance-wall section is arranged at a distance from a movement plane (120) of the cutting blade. The cutting blade is designed as a thread draw knife (37).

Description

The invention relates to a thread cutting device for a sewing machine according to the preamble of claim 1. Furthermore, the invention relates to a sewing machine with such a thread cutting device.

A thread cutting device of the type mentioned is known by public prior use. Other thread cutting devices are known from the DE 92 11 820 U1 , of the DE 10 2007 045 599 A1 and from a company publication Dürkopp Adler AG: 767 Special Sewing Machine, Service Manual, Edition 10/2008.

It is an object of the present invention, a thread cutting device of the type mentioned in such a way that their stability and in particular their reliability is improved.

This object is achieved by a thread cutting device with the features specified in claim 1.

According to the invention, it has been recognized that contact between the movable thread cutting knife and the counter knife is required only immediately adjacent to the actual cutting contact of the cutting edge with the counter edge. By the distance wall section ensures that this contact is not undesirable already prematurely. In the thread cutting device according to the invention, therefore, a smooth movement of the thread cutting blade is guaranteed to counter knife before the actual cutting process. The distance wall section is formed in particular by a hollow ground in the thread cutting knife. The counter knife can in particular on a gripper block of the sewing machine be set. In an adjustment of the gripper jaw is then automatically a co-adjustment of the counter blade, so that no realignment of the counter knife must be done. The spacer wall section can continuously merge into the upper thread cutter blade wall. The cutting plane of the thread cutting device can be oriented parallel to the plane of movement of the thread cutting blade during the cutting movement.

A design of the spacer wall section according to claim 2 ensures that there is not undesirable contact with the counter blade.

An adjustment range according to claim 3 allows a simple cutting force adjustment of the thread cutting device. In the adjustment range, there is a precisely defined relative position of the cutting edge of the thread cutting knife to the counter knife, which corresponds to a well-defined cutting force. The adjustment range may be marked for easier locating. This can be done for example by a laser marking.

A displaceable counter knife according to claim 4 allows a simple cutting force adjustment.

This applies correspondingly for a displaceable according to claim 5 counter knife.

Designs of a locking screw according to claims 6 and 7 advantageously combine several functions.

A thread-pulling knife according to claim 8 has proven itself in practice. The thread cutting device can be used to cut at least one upper thread and / or used for cutting at least one lower thread of the sewing machine.

The advantages of a sewing machine according to claim 9 correspond to those which have already been explained above with reference to the thread cutting device according to the invention. The sewing machine may be a one-needle sewing machine, a two-needle sewing machine, or a multi-needle sewing machine having a larger number of needles.

Fig. 1

eine bedienerseitige Ansicht einer Zwei-Nadel-Nähmaschine, wobei ein Maschinentisch zur Sichtbarmachung von in der Grundplatte untergebrachten Details weggelassen ist;

Fig. 2

eine perspektivische Ansicht der Zwei-Nadel-Nähmaschine nach Figur 1;

Fig. 3

aus der Blickrichtung nach Figur 1 und vergrößert eine Na- delstangen-Schaltbaugruppe der Nähmaschine, wobei beide Nadelstangen im oberen Totpunkt und in einem eingeschalte- ten Nähbetriebs-Zustand vorliegen;

Fig. 4

eine Ansicht der Nadelstangen-Schaltbaugruppe aus Blick- richtung IV in Figur 3;

Fig. 5

eine Ansicht der Nadelstangen-Schaltbaugruppe aus Blick- richtung V in Figur 4;

Fig. 6

in einer zu Figur 3 ähnlichen Darstellung die Baugruppe mit eingeschalteter linker Nadelstange im Bereich eines unteren Totpunktes und ausgeschalteter rechter Nadelstange;

Fig. 7

in einer zu Figur 4 ähnlichen Darstellung die Baugruppe im Schaltzustand nach Figur 6;

Fig. 8

in einer zu Figur 6 ähnlichen Darstellung die Baugruppe, bei der die Nadelstangen in einer Stellung nach Durchführung ei- ner Nadeltransport-Schwenkbewegung dargestellt sind und wobei im Vergleich zu Figur 6 einige Komponenten der Bau- gruppe weggelassen sind;

Fig. 9

in einer zu Figur 7 ähnlichen Darstellung die Baugruppe in der Nadeltransportstellung nach Figur 8;

Fig. 10

eine Ausschnittsvergrößerung im Bereich X. in Figur 9;

Fig. 11

in einer zu Figur 8 ähnlichen Darstellung die Baugruppe nach Durchführung der Nadeltransport-Schwenkbewegung;

Fig. 12

in einer zu Figur 7 ähnlichen Darstellung die Baugruppe in der Nadeltransportstellung nach Figur 11;

Fig. 13

eine Ausschnittsvergrößerung im Bereich XIII. in Figur 12;

Fig. 14

in einer zu Figur 4 ähnlichen Darstellung, allerdings unter Weglassung einiger Komponenten und im Bereich einer Schubwelle gebrochen und teilweise im Schnitt die Nadel- stangen-Schaltbaugruppe;

Fig. 15

vergrößert den Ausschnitt XV. in Figur 14;

Fig. 16

eine Ansicht der Baugruppe gemäß Blickrichtung XVI. in Figur 14;

Fig. 17

perspektivisch eine Hebelverbindung einer Nadelstangen- Transportvorrichtung der Nähmaschine in einer Transport- stellung einer Zugstange;

Fig. 18

eine Seitenansicht der Hebelverbindung nach Figur 17, gese- hen aus einer Blickrichtung parallel zu einer Längsachse der Schubwelle;

Fig. 19

einen Schnitt gemäß Linie XIX-XIX in Figur 18;

Fig. 20

in einer zu Figur 17 ähnlichen Darstellung die Hebelverbin- dung, wobei die Zugstange in einer Neutralstellung gezeigt ist;

Fig. 21

die Hebelverbindung in der Stellung nach Figur 20 in einer zu Figur 18 ähnlichen Darstellung;

Fig. 22

einen Schnitt gemäß Linie XXII-XXII in Figur 21;

Fig. 23

in einer zu Figur 20 ähnlichen Darstellung die Hebelverbin- dung mit gelöster Feststellschraube eines Nadeltransporthe- bels der Hebelverbindung;

Fig. 24

in einer zu Figur 21 ähnlichen Darstellung die Hebelverbin- dung in der Stellung nach Figur 23;

Fig. 25

perspektivisch eine Greiferantriebs-Baugruppe der Nähma- schine;

Fig. 26

perspektivisch eine Wellenanordnung der Greiferantriebs- Baugruppe;

Fig. 27

eine Seitenansicht der Wellenanordnung nach Figur 26;

Fig. 28

einen axialen Längsschnitt durch die Wellenanordnung ge- mäß Linie XXVIII-XXVIII in Figur 27;

Fig. 29

den Detailausschnitt XXIX in Figur 28;

Fig. 30

einen Schnitt gemäß Linie XXX-XXX in Figur 27;

Fig. 31

einen Schnitt gemäß Linie XXXI-XXXI in Figur 27;

Fig. 32

in einer zu Figur 31 ähnlichen Darstellung die Wellenanord- nung in einer ersten Randposition einer Schwenkverstellung einer Hohlwelle zur Einstellung eines Schleifenhubes;

Fig. 33

in einer zu Figur 31 ähnlichen Darstellung die Wellenanord- nung in einer gegenüberliegenden Randposition einer Schwenkverstellung einer Hohlwelle zur Einstellung eines Schleifenhubes;

Fig. 34

einen Schnitt gemäß Linie XXXIV-XXXIV in Figur 30;

Fig. 35

den Detailausschnitt XXXV in Figur 34;

Fig. 36

perspektivisch eine Fadenabschneider-Baugruppe der Näh- maschine;

Fig. 37

eine Aufsicht auf die Fadenabschneider-Baugruppe, im Be- reich einer Schneidkraft-Einstellschraube gebrochen;

Fig. 38

eine Seitenansicht der Fadenabschneider-Baugruppe gemäß Blickrichtung XXXVIII in Figur 37;

Fig. 39

vergrößert einen Ausschnitt der Fadenabschneider-Baugruppe im Bereich einer Messeranordnung aus einer zu Figur 38 ähn- lichen Blickrichtung in einer Position eines Fadenziehmessers relativ zu einem Gegenmesser nach einem Fadenabschneiden;

Fig. 40

den Detailausschnitt XL in Figur 39;

Fig. 41

eine interne Details im Bereich der Schneidkraft- Einstellschraube preisgebende Ansicht ähnlich zur Figur 39;

Fig. 42

eine Aufsicht auf die Messeranordnung in der Relativposition nach Figur 39;

Fig. 43

perspektivisch die Messeranordnung der Fadenabschneider- Baugruppe in einer Relativposition des Fadenziehmessers zum Gegenmesser vor dem Fadenabschneiden;

Fig. 44

in einer zu Figur 39 ähnlichen Darstellung die Messeranord- nung in der Relativposition nach Figur 43;

Fig. 45

das Detail XLV in Figur 44;

Fig. 46

in einer zu Figur 42 ähnlichen Darstellung die Messeranord- nung in der Relativposition nach Figur 43;

Fig. 47

perspektivisch eine Ansicht auf einen Ausschnitt der Mes- seranordnung mit Blickrichtung auf die Schneidkraft- Einstellschraube;

Fig. 48

die Messeranordnung in einer Relativposition des Faden- ziehmessers zum Gegenmesser bei einer Schneidkrafteinstel- lung;

Fig. 49

in einer zu Figur 44 ähnlichen Darstellung die Messeranord- nung in der Relativposition nach Figur 48;

Fig. 50

das Detail L in Figur 49;

Fig. 51

in einer zu Figur 46 ähnlichen Ansicht die Messeranordnung in der Relativposition nach Figur 48;

Fig. 52

in einer zu Figur 47 ähnlichen Darstellung die Anordnung in der Relativposition nach Figur 48;

Fig. 53

die Messeranordnung in der Relativposition nach Figur 39 perspektivisch gesehen mit Blickrichtung schräg von unten auf eine Unterfadenklemme, wobei das Gegenmesser wegge- lassen ist;

Fig. 54

in einer zu Figur 39 ähnlichen Darstellung die Messeranord- nung mit über eine Klemmkraft-Einstellschraube vorgespann- ter Fadenklemme;

Fig. 55

eine Ansicht gemäß Blickrichtung LV in Figur 54 in einer den Blick auf die Klemmkraft-Einstellschraube freigebenden gebrochenen Darstellung;

Fig. 56

die Messeranordnung in einer Fadenklemmkraft-Einstell- Relativposition des Fadenziehmessers zum Gegenmesser und zur Unterfadenklemme;

Fig. 57

in einer zu Figur 54 ähnlichen Darstellung die Messeranord- nung in der Relativposition nach Figur 56;

Fig. 58

in einer zu Figur 55 ähnlichen Darstellung die Messeranord- nung mit der Klemmkraft-Einstellschraube in Eingriff mit der Fadenklemme;

Fig. 59

eine Ausschnittsvergrößerung aus Figur 58 im Bereich der Unterfadenklemme;

Fig. 60

perspektivisch einen Ausschnitt der Grundplatte gesehen schräg von oben im Bereich einer Stichplatte und zweier an diese angrenzender Stichplattenschieber;

Fig. 61

eine Aufsicht auf den Grundplattenabschnitt nach Figur 60;

Fig. 62

einen Schnitt gemäß Linie LXII-LXII in Figur 61;

Fig. 63

das Detail LXIII in Figur 62 in einer Sicherungsstellung, in der der in der Figur 61 rechts dargestellte Stichplattenschieber gegen eine Relativverlagerung relativ zur Grundplatte gesi- chert ist;

Fig. 64

das Detail nach Figur 63 in einer Freigabestellung, in der eine Relativverlagerung des Stichplattenschiebers relativ zur Grundplatte ermöglicht ist;

Fig. 65

einen Schnitt gemäß Linie LXV-LXV in Figur 61; und

Fig. 66

das Detail LXVI in Figur 65.

An embodiment of the invention will be explained in more detail with reference to the drawings. In this show:

Fig. 1

a user side view of a two-needle sewing machine, wherein a machine table for visualization of housed in the base plate details is omitted;

Fig. 2

a perspective view of the two-needle sewing machine according to FIG. 1 ;

Fig. 3

from the perspective FIG. 1 and enlarges a needle bar shift assembly of the sewing machine with both needle bars in top dead center and in a powered sewing state;

Fig. 4

a view of the needle bar switching assembly from the direction of view IV in FIG. 3 ;

Fig. 5

a view of the needle bar switching assembly from the direction V in FIG. 4 ;

Fig. 6

in one too FIG. 3 similar representation of the assembly with activated left needle bar in the region of a bottom dead center and switched off right needle bar;

Fig. 7

in one too FIG. 4 similar representation of the module in the switching state after FIG. 6 ;

Fig. 8

in one too FIG. 6 a similar representation of the assembly, in which the needle bars are shown in a position after performing a Nadeltransport pivoting movement and wherein compared to FIG. 6 some components of the assembly have been omitted;

Fig. 9

in one too FIG. 7 Similar representation after the assembly in the needle transport position FIG. 8 ;

Fig. 10

an enlarged detail in the area X. in FIG. 9 ;

Fig. 11

in one too FIG. 8 similar representation of the assembly after carrying out the needle transport pivoting movement;

Fig. 12

in one too FIG. 7 Similar representation after the assembly in the needle transport position FIG. 11 ;

Fig. 13

an enlarged detail in the area XIII. in FIG. 12 ;

Fig. 14

in one too FIG. 4 similar illustration, but with the omission of some components and in the range of a shear wave broken and partially in section the needle bar switching assembly;

Fig. 15

enlarges the detail XV. in FIG. 14 ;

Fig. 16

a view of the assembly according to the viewing direction XVI. in FIG. 14 ;

Fig. 17

in perspective, a lever connection of a needle bar transport device of the sewing machine in a transport position of a pull rod;

Fig. 18

a side view of the lever connection to FIG. 17 , seen from a viewing direction parallel to a longitudinal axis of the shear wave;

Fig. 19

a section along line XIX-XIX in FIG. 18 ;

Fig. 20

in one too FIG. 17 similar representation of the lever connection, wherein the pull rod is shown in a neutral position;

Fig. 21

the lever connection in the position after FIG. 20 in one too FIG. 18 similar presentation;

Fig. 22

a section according to line XXII-XXII in FIG. 21 ;

Fig. 23

in one too FIG. 20 similar representation of the lever connection with loosened locking screw of a Nadeltransporthe- lever the lever connection;

Fig. 24

in one too FIG. 21 similar representation the lever connection in the position after FIG. 23 ;

Fig. 25

in perspective, a gripper drive assembly of the sewing machine;

Fig. 26

in perspective, a shaft arrangement of the gripper drive assembly;

Fig. 27

a side view of the shaft assembly according to FIG. 26 ;

Fig. 28

an axial longitudinal section through the shaft arrangement according to line XXVIII-XXVIII in FIG. 27 ;

Fig. 29

the detail XXIX in FIG. 28 ;

Fig. 30

a section along line XXX-XXX in FIG. 27 ;

Fig. 31

a section according to line XXXI-XXXI in FIG. 27 ;

Fig. 32

in one too FIG. 31 similar representation of the wave arrangement in a first edge position of a pivoting adjustment of a hollow shaft for setting a looping stroke;

Fig. 33

in one too FIG. 31 similar representation of the wave arrangement in an opposite edge position of a pivoting adjustment of a hollow shaft for setting a looping stroke;

Fig. 34

a section according to line XXXIV-XXXIV in FIG. 30 ;

Fig. 35

the detail XXXV in FIG. 34 ;

Fig. 36

in perspective, a thread trimmer assembly of the sewing machine;

Fig. 37

a view of the thread trimmer assembly, broken in the area of a cutting force adjustment screw;

Fig. 38

a side view of the thread trimmer assembly according to the viewing direction XXXVIII in FIG. 37 ;

Fig. 39

enlarges a section of the thread trimmer assembly in the range of a knife assembly from one to Figure 38 similar viewing direction in a position of a thread-pulling knife relative to a counter-knife after a thread trimming;

Fig. 40

the detail XL in FIG. 39 ;

Fig. 41

an internal details in the area of the cutting force adjusting screw similar to the FIG. 39 ;

Fig. 42

a plan view of the knife assembly in the relative position to FIG. 39 ;

Fig. 43

in perspective, the knife assembly of the Fadenabschneider- assembly in a relative position of the thread-pulling knife to the counter blade before the thread trimming;

Fig. 44

in one too FIG. 39 similar representation the Messeranord- tion in the relative position to FIG. 43 ;

Fig. 45

the detail XLV in FIG. 44 ;

Fig. 46

in one too Figure 42 similar representation the Messeranord- tion in the relative position to FIG. 43 ;

Fig. 47

in perspective, a view of a section of the knife arrangement with a view towards the cutting force adjusting screw;

Fig. 48

the knife arrangement in a relative position of the thread draw knife to the counter knife in a cutting force setting;

Fig. 49

in one too FIG. 44 similar representation the Messeranord- tion in the relative position to FIG. 48 ;

Fig. 50

the detail L in FIG. 49 ;

51

in one too FIG. 46 similar view of the knife assembly in the relative position to FIG. 48 ;

Fig. 52

in one too FIG. 47 similar representation according to the arrangement in the relative position FIG. 48 ;

Fig. 53

the knife assembly in the relative position to FIG. 39 seen in perspective, viewed obliquely from below on a lower thread clamp, the counter knife is omitted;

Fig. 54

in one too FIG. 39 similar representation of the knife assembly with biased by a clamping force adjustment screw thread clamp;

Fig. 55

a view according to the viewing direction LV in FIG. 54 in a view of the clamping force adjusting screw releasing broken representation;

Fig. 56

the knife assembly in a thread clamping force setting relative position of the thread-pulling knife to the counter knife and the lower thread clamp;

Fig. 57

in one too FIG. 54 similar representation the Messeranord- tion in the relative position to FIG. 56 ;

Fig. 58

in one too FIG. 55 similar representation of the knife assembly with the clamping force adjustment screw in engagement with the thread clamp;

Fig. 59

an excerpt from FIG. 58 in the area of the lower thread clamp;

Fig. 60

perspectively seen a section of the base plate obliquely from above in the region of a needle plate and two adjoining this Stichplattenschieber;

Fig. 61

a view of the base plate section after FIG. 60 ;

Fig. 62

a section according to line LXII-LXII in FIG. 61 ;

Fig. 63

the detail LXIII in FIG. 62 in a secured position, in which the in the FIG. 61 Right hand stitch plate slide is secured against a relative displacement relative to the base plate;

Fig. 64

the detail after FIG. 63 in a release position, in which a relative displacement of the needle plate slide relative to the base plate is made possible;

Fig. 65

a section according to line LXV-LXV in FIG. 61 ; and

Fig. 66

the detail LXVI in FIG. 65 ,

One with its main components in the FIGS. 1 and 2 shown two-needle sewing machine 1 has an upper arm 2, a vertical stand 3 and a lower housing in the form of a base plate 4. In the arm 2, an arm shaft is rotatably mounted, the Armwellenachse 5 in the FIGS. 14 and 16 is drawn. In the FIG. 14 the arm shaft axis 5 results as the intersection of two auxiliary lines 5a and 5b.

A housing 7 of the sewing machine 1 and the base plate 4 are part of a frame of the sewing machine. 1

A drive of the arm shaft and thus the essential sewing components of the sewing machine 1 via a mounted in the arm 2 drive motor. Other sewing components are driven by a belt drive not shown in detail in the drawing. About the arm shaft and one in the FIGS. 3 to 6 Drive device shown in more detail in the form of a crank drive 8 are two needle bars 9, 10 vertically driven up and down driven. The in the FIG. 1 Needle bar shown on the left is denoted by the reference numeral 9 and in the FIG. 1 Needle bar shown on the right is designated by the reference numeral 10 below. The needle bars 9, 10 each carry a needle 11, 12. The needle bars 9, 10 form a needle-receiving unit for the two needles 11, 12. Instead of two needle bars 9, 10 may in a not shown embodiment of the sewing machine 1, a single needle Receiving unit may be provided which receives both needles 11, 12.

Below the needle bars 9, 10, a needle plate 14 is arranged in an upper support plate 13 of the base plate 4 and screwed to the support plate 13. The throat plate 14 is in the Figures 60 and 61 shown in more detail. The throat plate 14 has two along a sewing direction 15 (see Figures 2 and 61 ) longitudinally extending feed dog openings 16, 17, which serve for the passage of a feed of the material to be conveyed feed gate with two feed valves sections 18, 19. The feed dog sections 18, 19 each have a tap hole 20, 21 for the passage of the respective associated needle 11, 12th

From above, the sewing material is held by means of a presser foot 22 during the sewing process. Via a magnetic drive 23 (cf. FIG. 1 ) Magnetic ventilation of the presser foot 22 is possible.

For advancing the material between the stitch plate 14 and the presser foot 22 during the sewing process serve either the feed dog sections 18, 19 or the piercing into the fabric needles 11, 12 itself. The sewing machine 1 can thus be operated either with a bottom feed or with a needle transport.

Below the throat plate 14, a gripper assembly 24 is arranged in the base plate 4, the total and with widely spaced grippers 25, 26 in the FIG. 25 is shown. A distance variation between the grippers 25, 26 and thus between the stitched with the needles 11, 12 and the associated grippers 25, 26 seams is possible in the sewing machine 1 in the range between a few and a few tens of millimeters.

The gripper tips 27 of the grippers 25, 26 act in concert with the movement of the needles 11, 12 in order to form a stitch, whereby a loop of an upper thread, not shown, into which the gripper tips 27 engage, is formed by the movement of the needle.

The grippers 25, 26 are designed as grippers rotating about vertical and mutually parallel axes and each have a needle storage housing 28 for a supply of a lower thread, which is in the form of a bobbin is provided. In stitch formation, one of the two lower threads made available by the grippers 25, 26 is knotted with one of the upper threads provided by the two needles 11, 12.

The two upper threads are provided by coils, not shown in the drawing and a needle thread tensioning device 29 (see FIGS. 1 and 2 ), which is mounted on a mounting plate of the arm 2, defined and adjustable tensioned.

To drive the feed dog with the feed dog sections 18, 19 is a Stichstellergetriebe 30, which in the Fig. 1 is visible in the base plate 4. A rotary drive of the grippers 25, 26 via a lower shaft 31 and via deflection, which are housed in each of the grippers 25, 26 associated gripper drive housing 32, 33.

To cut off the upper and lower threads serve two thread cutter assemblies, of which a thread cutter assembly 34 in total in the FIG. 36 is shown and of the in the FIGS. 1 and 2 a cutting cam 35 is visible, which via a solenoid 36 for actuating a thread-pulling knife 37 (see FIG. 36 ) is switchable. The cutting cam 35 is rotatably connected to the lower shaft 31.

In each case one of the two thread cutter assemblies 34 is responsible for cutting an associated pair of an upper thread and a lower thread.

For selectively switching off the sewing operation of one of the two needle bars 9, 10 is a switching device 38 of a needle bar switching assembly is used 39, the total in the FIGS. 3 to 7 and in details also in the FIGS. 8 to 16 is shown. With the switching device 38 can be changed between three operating states of the sewing machine 1. In a position of the switching device 38, which in the FIGS. 3 to 5 is shown, both needle bars 9, 10 are turned on, so take part in sewing. In the position of the switching device 38, which is shown in Figures 6 to 12, the left needle bar 9 is turned on, so takes part in sewing, and the right needle bar 10 is turned off, so remains in a rest position in the region of top dead center. Accordingly, via the switching device 38, a third operating position can be brought about, in which the right needle bar 10 is turned on and the left needle bar 9 is turned off.

In its basic operation, such a switching device is known from the DE-PS 955 023 ,

In the operating position in which both needle bars 9, 10 are turned on, the switching cam 40 is located between two switching pins 41, which are respectively arranged at the upper end of the two needle bars 9, 10 , In the respective switch-off position of the switching device 38, in which one of the two needle bars 9, 10 is turned off, the switching cam 40 acts via a lower switching active surface 42 (see FIG Figures 10 and 13 ) with the switching pin 41 at a switching end 43 of the respective needle bar together. For displacing the switching cam 40 between its various switching positions is a manually operable actuator 45 (see FIG. 3 ), which has a shift lever 46 and a reset lever 47. The actuating element 45 is mechanically connected to the switching cam via a horizontal shaft 48, a shift linkage 49 and an engagement lever 50 (see FIG. 10 ). In the region of an articulation of the shift linkage 49 on the horizontal shaft 48 is a return spring 51 (see FIG. 4 ), which cooperate with a stop unit 52, at the spring ends 53 of the return spring 51 cooperates. The stop unit 52 includes a stop pin 54 for the middle position of the switching cam 40 between the two switching pins 41st

To move the needle bars 9, 10 during a stitch along the sewing direction or transport direction 15, ie for needle transport, is a needle transport device 55, the needle bar side components, for example, in the FIGS. 3 and 5 are shown. The needle transport is carried out by pivoting a needle bar support 56 in the form of the two needle bars 9, 10 outside leading backdrop about a pivot axis 57. The pivot axis 57 is parallel to the support plate 13. The pivot axis 57 is from the switching cam 40 by more than 10 mm, in the illustrated embodiment by several cm, spaced. The pivoting about the pivot axis 57 is driven via a along this pivot axis 57 extending thrust shaft 58. A needle bar side end of the thrust shaft 58 is rotatably connected to the guide slot 56. The latter has an upper guide portion 59 which is connected to a lower guide portion 60. The latter is in turn rotatably connected via an actuating arm 61 with the thrust shaft 58.

The switching cam 40 is (see Figures 10 and 13 ) is configured such that the switching active surface 42 follows a pendulum movement due to the needle transport of the switching ends 43 of the needle bars. FIG. 10 shows the switching cam 40 in the needle transport position of the switching ends 43 toward the end of the needle transport process, ie in one position, in which the needle-side ends 44 of the needle bars 9, 10 are deflected maximally in the sewing direction 15. FIG. 13 shows the position of the switching ends 43, which corresponds to a maximum deflection of the needle bars against the sewing direction 15.

The switching cam 40 is pivotally mounted about a pivot axis 57 parallel to the switching cam pivot axis 62 on a housing-fixed switching cam carrier 63. For switching operation of the switching cam 40, the engaging lever 50 cooperates with the switching cam 40 via a driver 64 which is fixedly connected to the engaging lever 50, and an actuating groove 65 formed in the switching cam 40. In this way, a safe actuation adhesion between the engaging lever 50 and the switching cam 40 is independent of the pivotal position of the switching cam 40 to the switching cam pivot axis 62 guaranteed.

The engagement lever 50 is connected to the shift linkage 49 via a return spring 66 (see, for example FIG. 7 ). The return spring 66 ensures that the switching cam 40 at a lateral impact of this on one of the switching pins 41 each to be switched needle bar 9, 10 an actuating movement in the direction of this switching pin 41 to dodge so long against the bias of the return spring 66 until this switching pin 41 by a sewing movement of the respective needle bar 9, 10 has moved far enough for the displacement of the switching cam 40 in the switching position on the switching pin 41 down.

Based on FIGS. 3 to 16 is the detailed structure of the crank drive 8 for up and outgoing sewing operation of the needle bars 9, 10 clearly. To this crank drive 8 includes a reciprocally driven driver 67 in the form of a crosshead, which in a sewing state of the respective Needle bar 9, 10, for example, in the FIG. 5 is shown, between an upper operating stop, which is formed by a stop ring 68 for each of the two needle bars 9, 10, and a switchable via the switching device 38 lower operating stop 69 on the needle bar 9, 10 is axially fixed. The lower operating stop 69 is formed by three stop balls 70, which are disengaged with released switching pins 41 in a stop position. In this stop position, the stop balls 70 project outward beyond a jacket wall of the associated needle bars 9, 10, so that an effective outside diameter of the needle bar 9, 10 produced thereby is greater than an inside diameter of the respective needle bar guide of the crosshead 67.

Each of the two stop rings 68 is fixed axially to the associated needle bar 9, 10 with a clamping screw. The stop ring 68 thus represents an upper operating stop for the crosshead 67.

About a crank 71 is the crosshead 67 with the arm shaft (see arm shaft axis 5, for example, in the FIG. 5 ) in drive connection.

The upper guide portion 59 of the guide slot 56 has a lower leading edge 72 (see, for example FIG. 5 ). The lower guide portion 60 of the guide slot 56 has an upper leading edge 73. The latter is spaced below the lower leading edge 72.

The switching device 38 has a switchable lower rest stop 74 for each of the two needle bars 9, 10, which can be set by actuation of the respective switching pin 41 in a stop position (see FIG. 16 ). Each of the two lower resting stops 74 comprises three stop balls 70 in the manner of the stop balls of the lower operating stop 69. The stop balls 70 of the lower resting stop 74 act in the stop position, in turn, they outwardly beyond the outer shell wall of the respective needle bar 9, 10, with an inner bevel of the upper leading edge 73 of the lower guide portion 60 together.

At rest, ie in the off state with actuated switching pin 41, the switched-off needle bar 9, 10 between an upper rest stop 75 and the switchable lower rest stop 74 axially fixed to the guide slot 56 (see FIG. 16 ). The upper rest stop 75 is predetermined by the upper edge of the respective stop ring 68.

By actuation of the respective switching pin 41, the stop balls 70 are switchable between a recessed neutral position in which they have no stop action and on the shell wall of the respective needle bar 9, 10 projecting stop position in which the stop balls 70 have a stop action. With respect to the lower rest stop 74 means this abutment effect abutment of the stop balls 70 at the upper leading edge 73 of the lower guide portion 60 of the guide slot 56. With respect to the lower operating stop 69 means this stop action abutment of the stop balls 70 at a lower abutment edge of the Crosshead 67.

In the outwardly over the jacket wall of the respective needle bar 9, 10 projecting stop position of the lower operating stop 69 and the lower resting stop 74, the stop balls 70 are resilient in the direction biased the stop position. Accordingly, the lower rest stop 74 is thus designed so that it biases the respectively switched off needle bar 9, 10 resiliently in the direction of the upper rest stop 75. During operation of the needle bars 9 and / or 10, it must also be ensured that the upper edge of the stop rings 68 does not abut against the lower guide edge 72. To ensure this, the distance of the lower guide edge 72 of the upper guide portion 59 of the guide slot 56 must be exactly predetermined to the upper edge of the stop rings 68 at top dead center of this entraining crosshead 67. It is then also ensured that the crosshead 67 with the needle bar 9, 10 is turned off does not strike against the stop ring 68 clamped between the upper rest stop 75 and the lower rest stop 74.

To this distance setting is a distance adjustment 76, which is designed as an eccentric adjustment, which in detail in the FIG. 15 is shown. The pivot axis 57 of the thrust shaft 58, located in the FIG. 15 as an intersection of two auxiliary lines 57a, 57b, is an eccentricity E horizontally from a horizontal position of the arm shaft axis 5 (see auxiliary line 5a in the FIG. 15 ) spaced. About a Einstellverdrehung the thrust shaft 58, the position of the guide slot 56 in the vertical direction relative to the position of the needle bars 9, 10 and thus the distance of the lower guide edge 72 of the upper guide portion 59 of the guide slot 56 to this facing upper leading edge of the crosshead 67 set. This distance is minimally greater than the thickness of the stop rings 68 in the axial direction along the needle bar 9, 10. In the illustrated embodiment, the eccentricity E is 0.2 mm, that is less than 1 mm.

FIGS. 17 to 24 show further components of the needle conveyor 55 in the form of a lever connection 77. The lever connection 77 is housed in the stator 3 of the sewing machine 1. The lever connection 77 has a driving lever 78 which is non-rotatably connected to a horizontally and parallel to the thrust shaft 58 extending drive shaft 79 of the Stichstellergetriebes 30. Via a first connecting joint 80, the driving lever 78 is connected to a pull rod 81. About another connecting joint 82 in the form of a joint screw unit, the pull rod 81 is pivotally connected to a needle transport lever 83. The needle transport lever 83 is at its, a hinge axis 82a (see FIG. 19 ) of the further connecting joint 82 opposite end rotatably connected to the thrust shaft 58. In the needle transport position of the lever connection 77, which in the FIGS. 17 to 19 is shown, carried out an implementation of an intermittent movement of the drive shaft 79 in a pendulum motion (see double arrow 84) of the driving lever 78 and correspondingly in a pendulum motion (see double arrow 85) of the needle transport lever 83. Accordingly, the thrust shaft 58 is driven intermittently, so that a pendulum Transport movement of the needle bars 9, 10 between, for example, the two in the Figures 9 and 12 Transport items shown takes place.

FIGS. 20 to 22 show a neutral position of the lever connection 77, in which the needle conveyor 55 is out of force, ie in which no needle transport takes place. In this neutral position, the pull rod 81 exerts no drive effect on the needle transport lever 83, so that it remains in spite of the pendulum movement 84 of the driving lever 78 at rest. In this neutral position, the needle feed lever 83 is screwed tightly to a frame component 85a of the sewing machine 1 via the hinge screw 82.

In the neutral position, the pull rod 81 is connected to the needle transport lever 83 via a slot / pin connection 86 with a sliding pin 87 fixedly attached to the needle transport lever 83 and a slot 88 integrally formed on the pull rod 81. The slide pin 87 is press-fitted into the needle feed lever 83. The slot 88 is designed as a guide fork of the drawbar 81. Due to the long hole / pin connection 86, a longitudinal movement (see double arrow 89) of the drawbar 81 runs into the void while the pull rod 81 is secured to the needle transport lever 83 at the same time.

FIGS. 23 and 24 show a changeover position of the lever connection 77 for the changeover of this between the transport position after the FIGS. 17 to 19 and the neutral position after the FIGS. 20 to 22 , Here, the joint screw unit 82 is released. The needle feed lever 83 can then move from its fixed position to the FIGS. 20 to 22 in the FIG. 24 to be pivoted clockwise until the mounting position after the FIGS. 23 and 24 is reached. In this mounting position of the sliding pin 87 is disengaged from the slot 88, so that a conversion of the drawbar 81 between the in the FIGS. 20 to 24 shown neutral position and in the FIGS. 17 to 19 shown transport position is possible.

Based on FIGS. 25 to 35 the gripper assembly 24 is explained below, to which in addition to the two grippers 25, 26 still belongs a gripper drive assembly. The two grippers 25, 26 are each supported by a gripper block 90, 91. The gripper block 90 thereby belongs to the gripper 25 and to the needle bar 9 and constitutes part of the gripper drive housing 32. The gripper block 91 belongs to the gripper 26 and to the needle bar 10 and constitutes part of the gripper drive housing 33.

The FIGS. 26 to 35 show the lower shaft 31 with the components attached thereto in the region of the gripper block 90. A corresponding, rotated by 180 ° about a vertical axis symmetrical thereto formed arrangement is in the range of the gripper block 91 before.

The two gripper blocks 90, 91 are spaced from each other fixed to the lower shaft 31, which rotates synchronously with the movement of the needles 11, 12, that is, synchronously with the arm shaft.

In the region of each of the two gripper blocks 90, 91, the lower shaft 31 is surrounded by a respectively non-rotatably connected to the lower shaft 31 hollow shaft portion 92, 93. Each have a bevel gear 94 (see FIGS. 26 to 28 ), which is non-rotatably connected to the respective hollow shaft section 92, 93, is this hollow shaft section 92, 93 via a gripper drive shaft with the respective gripper 25, 26 in drive connection. The respective hollow shaft section 92, 93 thus rotates synchronously with the respective gripper 25, 26.

To fix the gripper blocks 90, 91 on the lower shaft 31 is a clamping threaded pin 95 which is screwed radially through a respective hollow shaft portion 92, 93 surrounding adjusting sleeve 96. The adjusting sleeve 96 has for this purpose a radial internal thread which is designed to be complementary to an external thread of the threaded pin 95. In each case one of the two adjusting sleeves 96 is assigned to one of the two gripper blocks 90, 91 and fixed thereto.

A clamping portion of the threaded pin 95 with end-side clamping surface 97 is through an opening 98 of the respective hollow shaft portion 92, 93 passed. A comparison of Figures 28 on the one hand and 31 to 33 on the other hand shows that the aperture 98 allows the respective hollow shaft section 92, 93 no axial play, but a game in the circumferential direction about a lower shaft axis 98a.

The clamping surface 97 abuts against a mating surface 99 complementary to this, which is embodied, for example, as a plane milling in a jacket wall 100 of the lower shaft 31. As an alternative to a planar design, the mating surface 99 may also be formed, for example, as a V-groove. In any case, the counter surface 99 is not rotationally symmetrical to the axis of rotation 98a of the lower shaft 31 executed.

The adjusting sleeve 96 is part of a fastening device 101 for maintaining a peripheral relative position of the respective hollow shaft section 92, 93 about the rotation axis 98a to the clamping threaded pin 95 even with the clamping surface 97 of the clamping threaded pin 95 released from the counter surface 99.

The fastening device 101 comprises, in addition to the adjusting sleeve 96, two further clamping threaded pins 102. These constitute a securing means which secures the adjusting sleeve 96 in its circumferential relative position to the respective hollow shaft section 92, 93. The two clamping threaded pins 102 are each guided through an internal thread of the adjusting sleeve 96, which is complementary to the external thread of the respective clamping threaded pin 102. An end-side clamping surface 103 of the clamping threaded pins 102 abuts against an outer jacket wall 104 of the respective hollow shaft section 92, 93. Adjacent to the area where the respective clamping grub screw 102 against the respective hollow shaft section 92, 93 clamped, in the respective hollow shaft section 92, 93 a wall thickness taper in the form of a recess 105 is executed.

The counter surface 99 has an extension along the axis of rotation 98 a of the lower shaft 31, which in the FIG. 28 is denoted by S. When in the FIG. 28 shown axial relative position of the clamping threaded pin 95 to the lower shaft 31 is the counter surface 99 axially above the clamping threaded pin 95 to the left and to the right by a possible axial displacement U over. At the axial height of the clamping threaded pin 95, the hollow shaft sections 92, 93 each have an inner wall thickness reinforcement in the form of a circumferential collar 105a.

By loosening the respective clamping threaded pin 95, the associated gripper block 90, 91 can be moved axially relative to the lower shaft 31, so that in particular the distance of the two gripper tips 27 can be adjusted to each other. Due to the maintenance of the circumferential position of the clamping threaded pin 95 to the lower shaft 31 during this adjustment process because of the complementary surfaces 97, 99 varies in this adjustment, since the respective hollow shaft section 92, 93 via the adjusting sleeve 96 and the two other clamping Grub screws 102 is fixedly connected to the clamping threaded pin 95, the circumferential relative position of the respective hollow shaft portion 92, 93 to the lower shaft 31 not. Thus, even after an adjustment of a distance between the two gripper blocks 90, 91 and the tightening of the clamping threaded pin 95, a synchronization of the gripper tips 27 with a looping of the needle bars 9, 10 ensures the correct upper thread detection.

For Schleifenhub adjustment can, as in the FIGS. 32 and 33 shown, the respective hollow shaft portion 92 about the rotation axis 98a, starting from a central position to FIG. 31 be adjusted. FIG. 32 shows such an adjustment by a circumferential angle V in a first circumferential direction and FIG. 33 a counter-adjustment by the same amount V in the circumferential direction opposite. Depending on the adjustment amount V, a synchronization of the hook tip 27 to the loop stroke position of the associated needle bar 9, 10 can be changed and thus adjusted.

The puncture 105 prevents a frictional contact of the clamping surface 103 of the respective clamping threaded pin 102 in the outer edge region of the clamping surface 103 and thus prevents unintentional rotation of the respective hollow shaft section 92, 93 to the lower shaft 31 during tightening of the clamping threaded pin 102nd

Before displacing the respective gripper jib 90, 91, fastening screws 106 are also loosened, with which the gripper jacks 90, 91 are bolted to the base plate 4 on the frame side.

At the respective hollow shaft section 92, 93 in addition to the bevel gear 94 each still a capsule fan cam 107 is attached.

In the area of the gripper blocks 90, 91, the lower shaft 31 is mounted in each case via a bearing 108.

FIGS. 36 to 59 show the thread trimmer assembly 34 completely or in subassemblies. A cutting movement of the thread pulling knife 37 is in the activated position of the solenoid 36 by rolling a follower body 109 on a cutting curve 110 of the cutting cam 35 causes. The follower body 109 is connected via a transmission member 111 on the one hand with a lifting ram 112 of the solenoid 36 and on the other hand with the thread-pulling knife 37 in operative connection (see FIG. 36 ). The transmission member 111 is mounted fixed to the housing so that it can perform a rotational movement about a shaft portion 113 of the transmission member 111.

To a thread cutting device 114 of the thread trimmer assembly 34 is in addition to the thread-pulling knife 37, which is a movable thread cutting knife, a fixed over the respective gripper block 90, 91 fixed to the frame of the sewing machine 1 counter knife 115th

The Figures 39 and 40 show the thread cutting device 114 immediately after thread cutting. A cutting edge 116 of the thread pulling knife 37 cooperates with the thread cutting kit a counter edge 117 of the counter knife 115 together. The cutting edge 116 is bounded on the one hand by a catching groove 118 of the thread-pulling knife 37 and on the other hand by a cutting wall section 119 of an upper thread-pulling knife wall 119a of the thread-pulling knife 37, which corresponds to a plane of movement 120 (cf. FIG. 40 ) of the thread pulling knife 37 coincides with the cutting movement thereof. On the other side of the cutting edge 116, ie on the side opposite the cutting wall section 119, the thread-pulling knife wall 119 a merges into a spacing wall section 121 spaced apart from the movement plane 120. The spacer wall portion 121 is formed by a hollow grinding of the upper thread-pulling knife wall 119a. Due to the distance wall portion 121 comes when thread cutting the thread-pulling knife, which corresponds to the movement arrow 122 in the Figure 42 when thread cutting moves, only adjacent to the cutting edge 116 with the counter blade 115 in contact.

A distance A of the distance wall portion 121 to the movement plane 120 (see FIG FIG. 40 ) increases strictly monotonically with increasing distance of the distance wall section 121 to the cutting edge 116 in the mathematical sense.

Provided on the spacer wall section 121 is an adjustment area 123 adjacent to the cutting edge 116 (see FIG FIG. 50 ). This one is in the FIG. 50 indicated by two vertical short boundary lines, which extend from the distance wall portion 121 downward. A distance B of the adjustment portion 123 from the cutting edge 116 (see FIG FIG. 50 ) is dimensioned so that a correct cutting force, ie a correct cutting pressure exerted by the thread-pulling knife 37 against the counter blade 115 during thread cutting at the cutting edge 116, then exists when the thread-pulling knife 37 force-free in the adjustment 123, ie without pressure on the counter knife 115th is applied. The adjustment portion 123 is marked on the upper thread-pulling knife wall 119a by a laser mark. A correct cutting pressure for the thread cutting builds up due to an overlap C (cf. FIG. 50 ) between a height of the opposite edge 117 in the adjustment region 123 and a height of the cutting edge 116.

For cutting force adjustment is the counter blade 115 between counter blade positions with different distances of the opposite edge 117 to the movement plane 120, ie with different overlaps C, displaced. For this purpose, the counter knife 115 is displaceable about a pivot joint 124 with pivot axis 125 between different pivot positions and for fixing a predetermined cutting force via a locking screw 126, that is, via a cutting force adjusting screw, fixed. The Locking screw 126 also serves to fix the counter blade 115 on a counter blade carrier 127 and thus on the respective gripper block 90, 91 on the frame of the sewing machine 1. About a release of the locking screw 126 is simultaneously a relative positioning of the counter knife 115 relative to the counter blade carrier 127 along a direction of movement possible, the in the Figure 42 is illustrated by a double arrow 128. Thus, an axial relative position of the counter blade 115 along the pivot axis 125 can take place via the position specification direction 128.

The pivot joint 124 has a propeller shaft with joint axis 129. At this counter-blade 115 is fixed by a fastening screw 130.

To set the cutting force, the locking screw 126 is first released. Then, the thread-pulling knife 37 is displaced relative to the counter blade 115 until the counter edge 117 opposes the adjustment portion 123 on the upper thread-pulling knife wall 119a. Then, the counter blade 115 is pivoted about the pivot axis 125 until the counter edge 117 rests centrally in the adjustment region 123 on the upper thread-pulling knife wall 119a without bias. Then, while maintaining this counter knife position, the locking screw 126 is tightened.

When thread trimming the thread-pulling knife 37 is initially in the FIGS. 43 to 47 position shown. Due to the hollow grinding in the region of the spacer wall section 121, the thread-pulling knife 37 initially does not come into contact with the counterknife 115. This also applies to the beginning of the thread-cutting movement of the thread-pulling knife 37 until the thread-pulling knife 37 has displaced relative to the counter-knife 115 to such an extent Thread pulling knife 37 in adjustment range 123 with the counter knife 115 comes into contact. During the further movement of the thread pulling knife 37, the predetermined cutting force builds up due to the overlap C, so that when the cutting edge 116 of the thread pulling knife 37 passes the counter edge 117 of the counter knife 115, a correct thread cutting takes place.

The hollow grinding of the spacer wall section 121 leads to a smooth running of the first movement section of the thread pulling knife 37 during the cutting movement.

In addition to the thread-pulling knife 37 and the counterknife 115, the thread-cutting device 114 also has a thread clamp 131 made of an elastic material, for example of spring steel. This thread works with the thread-pulling knife 37, which constitutes a counterbody, for clamping a thread cut knife 37 and the counter knife 115 Thread together. The thread clamp 131 is designed as a leaf spring and has a retaining spring end 132 (see FIG. 59 ), with which the thread clamp 131 on the counter blade carrier 127, which serves insofar as a supporting body, is fixed, and a free clamping end 133rd

An adjustment member 134, for example, in the FIG. 55 is used to adjust a clamping pressure of the thread clamp 131 against the thread-pulling knife 37. The adjusting member 134 is displaced and acts between the two spring ends 132, 133 an adjustable pressure on the thread clamp 131 from. The adjusting member 134 is formed as screwed into the counter blade carrier 127 and self-locking running adjustment screw.

In the position after the FIGS. 53 to 55 the adjusting screw 134 is set in a neutral position and is not engaged with the thread clamp 131. In this position, the clamping end 133 of the thread clamp 131 is under slight thread tension on the thread-pulling knife 37, as far as the latter is present in the position after the thread cutting.

Figures 56 to 59 show the adjusting member 134 in engagement with the thread clamp 131. The thread clamp 131 is lifted between the holding spring end 132 and the clamping end 133 due to the action of the adjusting member 134 of a support wall 135 of the counter knife support 127, so that the clamping end 133 stronger presses against the thread-pulling knife 37, as far as the latter is present in the position after thread trimming. On the strength of the engagement of the adjusting member 134 with the thread clamp 131, this bias between the clamping end 133 and the thread-pulling knife 37 can be adjusted. This setting can be made in the clamping position of the thread clamp 131 relative to the thread-pulling knife 37.

FIGS. 60 to 66 show details of the support plate 13 in the throat plate 14. The throat plate 14 is fixed to the support plate 13 and thus to the base plate 4. An upper side of the throat plate 14 is aligned with an upper side of the surrounding support plate 13.

In the FIG. 61 left and right next to the throat plate 14 are two removable from the support plate 13 stitch plate slide 136, 137 fixed to the support plate 13 and thus on the base plate 4. The tops of the two throat plate sliders 136, 137 are aligned with the top of the throat plate 14 and with the top of the plate plate shifters 136, 137 surrounding the support plate 13. The two needle plate slide 136, 137 provide a removable cover housed in the base plate housing components of the sewing machine, in particular the gripper 25, 26 is.

In each case via a safety device 138 (see FIGS. 63 and 64 ), the two needle plate slides 136, 137 are secured against relative displacement of the needle plate slides 136, 137 relative to the support plate 13 and thus relative to the base plate 4. The securing device 138 will be described below in connection with that in the FIG. 61 right stitch plate slider 137 explained. Point symmetrical about a center between the two tap holes 20, 21 arranged for this purpose is the securing device 138 for in the FIG. 61 left needle plate slide 136.

The securing device 138 has a puncture resistant locking lug 139, which represents an integral portion of a leaf spring 140 which is fixed to the needle plate slide 137. The leaf spring 140 is biased in a securing position shown in the figure 63. In this, the locking lug 139 engages behind an undercut of a detent groove 141. The detent groove 141 is part of a detent plate 141 a, which is fixed via a fastening screw 141 b on the support plate 13 and thus on the base plate 4. The leaf spring 140 is accommodated between the needle plate pusher 137 and a clamping plate 142 which is displaceable relative thereto perpendicular to the surface of the needle plate pusher 137.

In the in the FIG. 63 illustrated securing position of the securing device 138 is a displacement of the needle plate slide 137 in a direction of movement 143, ie away from the throat plate 14, not possible. In the securing position, the needle plate slide 137 is thus against a relative displacement the needle plate slide 137 relative to the support plate 13 and thus secured to the base plate 4.

With a release device 144, the securing device 138 can be switched between the securing position and a release position, which in the FIG. 64 is shown and in which a relative displacement in the direction of movement 143 of the needle plate slide 137 relative to the support plate 13 and thus to the base plate 4 is possible. In the release position comes, as in the FIG. 64 shown, the locking lug 139 of the locking groove 141 free.

The release device 144 is executed by a release button, which is accessible from the top of the support plate 13 and thus from the top of the base plate 4 ago and cooperates with the locking lug 139. This interaction takes place indirectly by applying pressure via the release button 144 in the FIG. 63 from above via an actuating plunger 145, the clamping plate 142 and thus also the leaf spring 140 with the locking lug 139 down to the release position FIG. 64 is relocated. After reaching the release position of the needle plate slide 137 can be moved together with the release button 144 in the direction of movement 143 relative to the support plate 13 and thus away from the throat plate 14 away.

During the sliding movement of the needle plate slide 137 along the direction of movement 143, this is guided on the support plate 13 and thus on the base plate 4 via a guide device 146. The latter is formed by a guide groove 147 in the support plate 13 and thus in the base plate 4, in which a spring 148, which is part of the leaf spring 140, engages. Due to the spring action of the leaf spring 140 in the guide device 146 can be adjusted relative to the top of the platen 13 by means of adjusting screws an aligned position of the top of the needle plate slide 137.

As a tool for adjusting a game between the locking lug 139 and the locking groove 141 is used in the factory assembly of the sewing machine 1, a pin 149 which passed from above via a game opening 150 and a fitting opening 151 on the one hand through the needle plate slide 137 and on the other hand by the leaf spring 140 is. By a pivoting movement of the pin 149 (see double arrow 152 in the FIG. 62 ), a distance of the latching lug 139 to the latching groove 141 along the direction of movement 143 can be finely specified when resting on the throat plate 14 stitch plate slide 137.

The clamping plate 142 is screwed to the needle plate slide 137 via fastening screws 153.

Claims (9)

1. Thread cutting device (114) for a sewing machine (1), the thread cutting device (114) comprising

   - a movable thread cutting knife (37);

   - a counter knife (115) which is securely fixable to a sewing machine frame (4);

   - with a cutting edge (116) of the thread cutting knife (37), which cutting edge (116) interacts with a counter edge (117) of the counter knife (115) when cutting threads, the cutting edge (116) being bounded by a cutting wall portion (119) of an upper thread cutting knife wall (119a) of the thread cutting knife (37), the cutting wall portion (119) coinciding with a movement plane of the thread cutting knife (37) during the cutting movement thereof,

   characterized in that
   beyond the cutting edge (116), the upper thread cutting knife wall (119a) passes over into a distance wall portion (121) which is spaced from the movement plane (120) so that when cutting threads, the thread cutting knife (37) will not come into contact with the counter knife (115) until it is adjacent to the cutting edge (116).
2. Thread cutting device according to claim 1, characterized in that the distance (A) of the distance wall portion (121) from the movement plane increases strictly monotonically with increasing distance from the cutting edge (116).
3. Thread cutting device according to claim 1 or 2, characterized in that on the distance wall portion (121), an adjustment region (123) is provided which is adjacent to the cutting edge (116) and in which the counter knife (115) abuts the thread cutting knife in a force-free manner for adjusting a cutting force.
4. Thread cutting device according one of claims 1 to 3, characterized in that for cutting force adjustment, the counter knife (115) is displaceable between counter knife positions with different distances of the counter knife (115) to the movement plane (120).
5. Thread cutting device according to claim 4, characterized in that the counter knife (115) is displaceable about a pivot joint (124) between different pivoting positions.
6. Thread cutting device according to claim 5, characterized in that a locking screw (126) for fixing the pivot joint (124) is at the same time used for fixing the counter knife (115) to the sewing machine frame (4).
7. Thread cutting device according to one of claims 1 to 6, characterized in that a locking screw (126) for fixing the pivot joint (124) is at the same time used for defining an axial relative position of the counter knife (115) along a pivot axis (125) of the pivot joint (124).
8. Thread cutting device according to one of claims 1 to 7, characterized in that the thread cutting knife (37) is a thread pulling knife.
9. Sewing machine comprising a thread cutting knife (114) according to one of claims 1 to 8.

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